pofo
Aluminum
- Joined
- Feb 8, 2009
- Location
- california USA
I had another thread about a thermal relay, but that is not the problem. I'm stumped on what is wrong.
Symptoms
When I engage the spindle lever to forward with the motor off (the motor has a switch (ICS in the schematic below) that selects 3/6 hp, and it also has an off position), the contactors 1M and 2MF energize as is normal. All is good. Everything is energized the way it should be, except no power is reaching the motor since switch ICS, is off.
When I do the same with the motor switch on, the motor comes on for a fraction of a second and then 1M de-engergizes.
Debugging
I checked phases at the output of 2MF to the motor switch: 225, 235, 240volts.
I bypassed the thermal relay (IOL). No change. As you can see, the only things that can keep 1M from energizing are the emergency cutoff, the door interlock, the thermal relay, and 1M itself once engergized. Also note that 1SAS, iLS, 2LS are part of an electro-magnetic brake are disabled and remain in their normal positions. Once 2MF is energized, 1M must stay energized to keep both relays energized. You can see this in the circuit where the master stop is located. So it seems that 1M has a bad contact. I disassembled 1M and cleaned everything up. Still it drops out.
I next attempt to bypass 1M by forcing it in the engage position. When I do this, 2MF rattles on and off at a very rapid rate. You can see that nothing can de-energize 2MF except the spindle switch (remember that 1SAS stays in the closed position). I can observe 3MR and it is not energizing, which would de-energize 2MF.
To me, this seems to say that the 110volts from the transformer is dropping out low enough to de-energize the contactors when the motor loads the mains. The scenario is that 1M engages, the motor engages, the 110volts drops and then 1M drops.
When I force 1M, the motor starts, the 2MF drops, disconnects the motor, the 110 comes back up, 2MF engages, and it repeats.
I don't have a very sensitive meter, but the motor looks like it is not shorted. So I'm thinking that I have a bad connection that won't support the load when the motor comes on. I've checked everything and it looks good.
Any other ideas?
Symptoms
When I engage the spindle lever to forward with the motor off (the motor has a switch (ICS in the schematic below) that selects 3/6 hp, and it also has an off position), the contactors 1M and 2MF energize as is normal. All is good. Everything is energized the way it should be, except no power is reaching the motor since switch ICS, is off.
When I do the same with the motor switch on, the motor comes on for a fraction of a second and then 1M de-engergizes.
Debugging
I checked phases at the output of 2MF to the motor switch: 225, 235, 240volts.
I bypassed the thermal relay (IOL). No change. As you can see, the only things that can keep 1M from energizing are the emergency cutoff, the door interlock, the thermal relay, and 1M itself once engergized. Also note that 1SAS, iLS, 2LS are part of an electro-magnetic brake are disabled and remain in their normal positions. Once 2MF is energized, 1M must stay energized to keep both relays energized. You can see this in the circuit where the master stop is located. So it seems that 1M has a bad contact. I disassembled 1M and cleaned everything up. Still it drops out.
I next attempt to bypass 1M by forcing it in the engage position. When I do this, 2MF rattles on and off at a very rapid rate. You can see that nothing can de-energize 2MF except the spindle switch (remember that 1SAS stays in the closed position). I can observe 3MR and it is not energizing, which would de-energize 2MF.
To me, this seems to say that the 110volts from the transformer is dropping out low enough to de-energize the contactors when the motor loads the mains. The scenario is that 1M engages, the motor engages, the 110volts drops and then 1M drops.
When I force 1M, the motor starts, the 2MF drops, disconnects the motor, the 110 comes back up, 2MF engages, and it repeats.
I don't have a very sensitive meter, but the motor looks like it is not shorted. So I'm thinking that I have a bad connection that won't support the load when the motor comes on. I've checked everything and it looks good.
Any other ideas?